This invention relates to a thermoplastic polymer composition having a good compatibility with blood and to medical devices made of the thermoplastic polymer composition.
Research and development to equip medical devices with an anti-thrombotic property have become active recently. The method used for equipping medical devices with an anti-thrombotic property is to coat the surfaces (particularly the parts of them which contact with blood) of medical devices made of synthetic resins with anti-thrombotic substances. The anti-thrombotic substances used are fibrinolytic substances (urokinase, streptokinase, etc.), anti-thrombogenic substances (polysaccharides, prostaglandin, etc.), and neointima formation accelerating substances. The coating of a protease inhibiting substance is formed by application or chemical bonding (ionic or covalent bond).
The conventional method for equipping medical devices with an anti-thrombotic property thus needs a separate process for applying or chemically binding a protease inhibiting substance to the surfaces of the medical devices formed in the prior process, which requires a high level of technology according to the medical devices manufactured, the substances used, and other conditions.
In addition, the formation by application has the problems of an unsatisfactory durability of the coating and changes in the dimensions of medical devices (increase of the external diameter and decrease of the internal diameter) caused by the coating. It often needs an appropriate binder and also needs a solvent for dissolving or dispersing the protease inhibiting substance and binder to apply. The residual binder and solvent must be removed from the coating formed.
The formation by chemical bonding, on the other hand, needs a complicated process to introduce ionic groups or groups with a covalent bond forming ability into both the surface of the medical device and the protease inhibiting substance. Further, the group-introduction process can restrict the kind of material and protease inhibiting substance usable for the medical device to be manufactured. It can deteriorate partly or completely the anti-thrombotic property of the protease inhibiting substance because of the denaturation caused by ionic or covalent bonding. It also increase the cost of the medical device manufactured.
Moreover, it is difficult to form a coating of a protease inhibiting substance over the portions of the surface put in contact with blood of medical devices formed beforehand evenly with no areas left uncovered, particularly when the shapes of the medical devices are very complicated.
The object of this invention is to provide a novel thermoplastic polymer composition which can provide the entire body of medical devices with a compatibility with blood, especially an anti-thrombotic property, and medical devices made of the thermoplastic polymer composition.